HSP26/YBR072W Summary Help

Standard Name HSP26 1, 2
Systematic Name YBR072W
Feature Type ORF, Verified
Description Small heat shock protein (sHSP) with chaperone activity; forms hollow, sphere-shaped oligomers that suppress unfolded proteins aggregation; oligomer activation requires heat-induced conformational change; also has mRNA binding activity (3, 4, 5, 6, 7 and see Summary Paragraph)
Name Description Heat Shock Protein 1, 2
Chromosomal Location
ChrII:382030 to 382674 | ORF Map | GBrowse
Gene Ontology Annotations All HSP26 GO evidence and references
  View Computational GO annotations for HSP26
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 32 genes
Classical genetics
Large-scale survey
66 total interaction(s) for 56 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 39
  • Affinity Capture-RNA: 3
  • Affinity Capture-Western: 1
  • Biochemical Activity: 1
  • Co-localization: 2
  • Protein-peptide: 1
  • Reconstituted Complex: 3
  • Two-hybrid: 5

Genetic Interactions
  • Negative Genetic: 6
  • Phenotypic Enhancement: 4
  • Synthetic Growth Defect: 1

Expression Summary
Length (a.a.) 214
Molecular Weight (Da) 23,879
Isoelectric Point (pI) 5.22
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrII:382030 to 382674 | ORF Map | GBrowse
Last Update Coordinates: 2011-02-03 | Sequence: 1997-01-28
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..645 382030..382674 2011-02-03 1997-01-28
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
External Links All Associated Seq | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Primary SGDIDS000000276

HSP26 and HSP42 encode the cytosolic members of the small heat shock protein (sHSP) family of molecular chaperones (2, 8). sHSPs bind and prevent unfolded substrate proteins from irreversibly forming large protein aggregates. Bound substrate proteins can eventually be released and refolded in either a spontaneous or chaperone-assisted manner (reviewed in 9). Hsp42p functions in both unstressed and stressed cells, while Hsp26p activity is found only under stress conditions; the target substrate profiles of the two chaperones overlap by approximately 90% (10). Null mutations in hsp26 or hsp42 cause abnormal cell morphology that resembles the effects of dehydration, aging, cytoskeleton damage, or cell wall damage (10).

The HSP26 transcript is undetectable in unstressed cells but is strongly induced by heat shock, salt shock, cell cycle arrest, nitrogen starvation, carbon starvation, oxidative stress, and low pH (11, 12 and reviewed in 9). Under these conditions of stress, HSP26 expression is upregulated by the transcription factors Hsf1p and Msn2p/Msn4p which respectively bind heat shock elements and stress elements found in the HSP26 promoter (12).

Twelve Hsp26p dimers assemble to form a 24-subunit homo-oligomeric complex shaped like a hollow sphere (13, 14). Elevated temperature is required to activate this complex: heat shock causes a conformational change in Hsp26p that enables the complex to bind substrate proteins (6 and references therein). Higher temperatures also coincide with the disassociation of the complex back into dimers and it had been thought that these dimers were the active form of Hsp26p. However, it has been more recently shown that dimer reformation is not necessary for Hsp26p activation and chaperone function (13, 15).

All sHSP chaperones contain a highly conserved alpha-crystallin domain in their C-terminus, and sHSPs have been identified in archaea, plants, insects, cows, and humans (6, 1). Mutations in human sHSPs have been linked to the cardiovascular disorder desmin-related myopathy (OMIM), the neuromuscular disease Charcot-Marie-Tooth disease (OMIM), distal hereditary motor neuropathy (OMIM), and hereditary cataracts (OMIM) (14 and references therein).

Last updated: 2007-07-26 Contact SGD

References cited on this page View Complete Literature Guide for HSP26
1) Bossier P, et al.  (1989) Structure and expression of a yeast gene encoding the small heat-shock protein Hsp26. Gene 78(2):323-30
2) Petko L and Lindquist S  (1986) Hsp26 is not required for growth at high temperatures, nor for thermotolerance, spore development, or germination. Cell 45(6):885-94
3) Bentley NJ, et al.  (1992) The small heat-shock protein Hsp26 of Saccharomyces cerevisiae assembles into a high molecular weight aggregate. Yeast 8(2):95-106
4) Susek RE and Lindquist S  (1990) Transcriptional derepression of the Saccharomyces cerevisiae HSP26 gene during heat shock. Mol Cell Biol 10(12):6362-73
5) Rossi JM and Lindquist S  (1989) The intracellular location of yeast heat-shock protein 26 varies with metabolism. J Cell Biol 108(2):425-39
6) White HE, et al.  (2006) Multiple distinct assemblies reveal conformational flexibility in the small heat shock protein Hsp26. Structure 14(7):1197-204
7) Tsvetanova NG, et al.  (2010) Proteome-Wide Search Reveals Unexpected RNA-Binding Proteins in Saccharomyces cerevisiae.LID - e12671 [pii] PLoS One 5(9)
8) Wotton D, et al.  (1996) Multimerization of Hsp42p, a novel heat shock protein of Saccharomyces cerevisiae, is dependent on a conserved carboxyl-terminal sequence. J Biol Chem 271(5):2717-23
9) Burnie JP, et al.  (2006) Fungal heat-shock proteins in human disease. FEMS Microbiol Rev 30(1):53-88
10) Haslbeck M, et al.  (2004) Hsp42 is the general small heat shock protein in the cytosol of Saccharomyces cerevisiae. EMBO J 23(3):638-49
11) Carmelo V and Sa-Correia I  (1997) HySP26 gene transcription is strongly induced during Saccharomyces cerevisiae growth at low pH. FEMS Microbiol Lett 149(1):85-8
12) Amoros M and Estruch F  (2001) Hsf1p and Msn2/4p cooperate in the expression of Saccharomyces cerevisiae genes HSP26 and HSP104 in a gene- and stress type-dependent manner. Mol Microbiol 39(6):1523-32
13) Haslbeck M, et al.  (1999) Hsp26: a temperature-regulated chaperone. EMBO J 18(23):6744-51
14) Ferreira RM, et al.  (2006) Purification and characterization of the chaperone-like Hsp26 from Saccharomyces cerevisiae. Protein Expr Purif 47(2):384-92
15) Franzmann TM, et al.  (2005) The activation mechanism of Hsp26 does not require dissociation of the oligomer. J Mol Biol 350(5):1083-93